Field of the Invention
The present invention relates to a process for increasing resistance to penetration through a glazed opening, and also to glazing having break-in resistance reinforced by lamination.
Glazed openings equipped with single glazing of standard thickness, comprising for example a sheet of 4 millimeter glass, generally do not possess great resistance to penetration even if the glass has undergone thermal tempering treatment. A thief or vandal equipped with relatively simple means, such as a crowbar or sledgehammer, will not need much time to overcome the obstruction offered by such glazing and commit his misdeed. This is for example the case with ordinary door and window glazing in buildings such as dwellings. Another field requiring particular attention at the present time is that of motor vehicles or caravans, for example residential caravans. The ordinary glazing of a standard vehicle cannot long withstand the attention of a vandal. A thief can relatively easily break the side windows of the vehicle, which are generally in the form of single glass panes, and steal some of its contents or even the vehicle itself.
It is true that armoured windows or armoured vehicles exist in which the glazing is even bullet-proof. It is however quite clear that such glazing is very expensive, that it is heavy, and that in addition it needs a special frame or casing to receive its great thickness. In the case of a vehicle, for example, the extra cost required to improve the protection of the vehicle and its contents soon becomes very substantial. In any case, it may be very difficult or even impossible to fit armoured glazing of this kind to an ordinary standard production model of a vehicle.
The time required to break into the space enclosed by the glazed opening may be a determining element for the success or failure of the break-in. Lengthening this time is certainly a deterrent factor.